Why is my Preamp making noises..??

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Delta77

Why is my Preamp making noises..??
« on: 9 Nov 2017, 12:15 am »
My preamp is making noises. Any Ideas why..?  6 months old..
I’m getting “scratching , popping” noises in the speakers. Even when the system is muted or on pause..
The noise comes from out of nowhere and, will last only about 5 to 10 seconds , then goes away..
So I rolled the Tubes (2) - 12au7 .. I have 3 sets of Tubes , and all 3 sets made similar noises..
So I swapped the Power Cables, and RCA’s, (not the culprit)..
I removed the preamp from the system, running only the OPPO 205 to the Odyssey Amp for 2 weeks..
No noises, at all.. IS IT THE TUBES ..???

srb

Re: Why is my Preamp making noises..??
« Reply #1 on: 9 Nov 2017, 12:31 am »
It's possible that all three sets of tubes are faulty, but not extremely likely.  My thought would be that the tube sockets themselves need cleaning and deoxidizing with a contact cleaner and/or the pin contacts need to be re-tensioned if the socket design allows it.

Steve

jules

Re: Why is my Preamp making noises..??
« Reply #2 on: 9 Nov 2017, 03:56 am »
Analytical question ... Are both channels producing exactly the same noise at exactly the same time?

Delta77

Re: Why is my Preamp making noises..??
« Reply #3 on: 9 Nov 2017, 04:30 am »
No .. I only heard the noise on the right channel, since the last tube roll..
Really not positive, before the last roll..

jules

Re: Why is my Preamp making noises..??
« Reply #4 on: 9 Nov 2017, 05:18 am »
Ok, I'd agree with Steve on the idea of doing some maintenance work on the tube sockets, particularly as a first step. Avoid wiggling the tubes around while the pre-amp is on to see if it makes any difference. It can cause damage.

geerock

  • Jr. Member
  • Posts: 9
Re: Why is my Preamp making noises..??
« Reply #5 on: 10 Nov 2017, 03:46 pm »
Check your speaker connections.
Make sure they're clean and tight.

AlTran

Re: Why is my Preamp making noises..??
« Reply #6 on: 10 Nov 2017, 04:59 pm »
Delta77, what are the brand & make of those 3 pair tubes? Were those tested?   

A_shah

  • Jr. Member
  • Posts: 117
Re: Why is my Preamp making noises..??
« Reply #7 on: 10 Nov 2017, 06:19 pm »
Burt,
1.Tap slightly each one of these tubes with a pencil and see which is microphonic
2. As some one suggested make sure they fit tightly in the socket (don't break them :nono:
3. Don't Tube roll that often :) just listen to the Music once satisfied just leave it there
Cheers !
Asghar

richidoo

Re: Why is my Preamp making noises..??
« Reply #8 on: 10 Nov 2017, 09:13 pm »
Does the sound happen at any particular time, like right after unmuting, or at start up?

A dirty volume pot or signal switch would be silenced on mute. It is interesting that it happens when muted, suggesting the mute switch is on input side of the amplifier circuit rather than output. Makes the preamp noise less obvious when muting.

Rarely, a metal oxide resistor will crack inside, and it can make weird unpredictable noises like that. Noise could fade away as the resistor heats up and expands to make better contact. But those resistors are pretty hard to damage. I would send it in for repair before high voltage DC does more damage.

Delta77

Re: Why is my Preamp making noises..??
« Reply #9 on: 10 Nov 2017, 09:39 pm »
Double checked the connections on speakers and amp.
Brands  - JJ  (stock)
           - Gold Lion
           - RCA , cleartop

I pulled the everything out and Dusted/Cleaned today..
I really doubt that’s gonna fix anything, but my fingers are crossed..
Alex texted me back yesterday, he is on vacation overseas, and will get back to me as soon as he returns..
Thanks for everyone’s help ..

klaus@odyssey

Re: Why is my Preamp making noises..??
« Reply #10 on: 11 Nov 2017, 01:24 am »
I don't know if it is the tubes here...Alex would know best,  but he's back home in Chile right now for the next couple of weeks...maybe he'll monitor the circle and chime in,  but either way,  we'll be glad to take a look and check out the Candela for sure...just in case